Plasma confining device



March 1955 H. LEBOUTET ETAL PLASMA CONFINING DEVICE Filed April 19, 1960 INVENTORS HUBERT LEBOUTEI' JEANMICHEL DOLIQUE ATTORN Y United States Patent Ofifice 3,174,068 Patented Mar. 16, 1965 794,6 8 Claims. (Cl. 313161) The present invention relates to devices utilizing an annular enclosure or vessel in which a plasma of a light element, such as deuterium, is confined within the interior of the space enclosed by the vessel in order to insulate the same from the walls so that the particles of the plasma cannot impinge thereagainst and thereby cause energy losses.

It is known in the prior art that such devices may be utilized as neutron generators and generators of nuclear energy if one achieves to confine the particles during a sufiiciently long time so that the nuclear reactions due to shocks or impacts between these particles carried at relatively very high kinetic temperatures have the time to produce at least as much energy as the plasma loses as a result of impacts against the walls, oontaminations, etc.

One of the most widely accepted practices to produce the confinement is to place the interior space of the enclosure or vessel filled within plasma within a magnetic field of an intensity which is constant in time at each point, and of which the lines of force are essentially parallel to the walls from which the plasma has to be insulated.

It is also known in the prior art, in connection with the enclosures or vessels of linear form, to produce near the ends or extremities of such enclosures, constrictions of the lines of force, so-called magnetic mirrors or throats of magnetic bottle, by means of auxiliary magnetic coils or windings producing a much more intense magnetic field at the places of these throats. Such auxiliary windings could be avoided, in principle, if the enclosure or vessel has an annular shape; for by reason of the closure of the interior space upon itself, the axial movement of the particles entrains only the circulation thereof in a circle and does not mean the escape thereof toward the walls, escape gainst which seek to counteract the magnetic mirrors in a linear enclosure, at least insofar as the longitudinal escape thereof is concerned.

It has been found that also in connection with annular enclosures or vessels it is equally advantageous to provide magnetic mirrors distributed in a certain number at points along the extent of the annulus, precisely to reduce such circulation in circle form in such a manner as to impede the movement as a whole of the mass of the plasma, a movement of which the effects are unfavorable as can be readily demonstrated in practice insofar as the maintenance of high kinetic temperatures is concerned.

However, even in connection with an annular enclosure provided with magnetic mirrors distributed in a certain number at points along the extent of the annulus, the confinement realizable thereby is not suflicient, particularly by reason of the diffusion of particles across the lines of force of the magnetic field which may, therefore, escape from the mass of the plasma and will fall on or impinge against the walls of the enclosure.

Accordingly, it is a primary object of the present invention to provide a device of the type described hereinabove including an annularly-shaped enclosure provided with magnetic mirrors in which the transverse escape of the particles is substantially eliminated or at least considerably reduced.

It is another object of the present invention to provide a particle confining device combining the advantages of both the conventional annular confining device and the conventional linear confining device while at the same time increasing the tightness of the magnetic bottle used with the present invention.

Still a further object of the present invention is the provision of means in connection with an annularlyshaped confining device provided with so-called magnetic mirrors which reduces the losses of energy in the plasma due to escape or impingement against the walls of the enclosure or envelope.

Still another object of the present invention is the provision of a particle confining device having all the advantages described hereinabove which is both simple in structure, relatively inexpensive in manufacture and which nonetheless provides a high degree of efiiciency for the intended purposes.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention.

According to the present invention the plasma contained within an annular enclosure or vessel provided with magnetic mirrors is confined therein, not only by the static magnetic field, but also by an electromagnetic field of a high-frequency wave propagating in a closed circuit or loop within the conduit formed between the plasma and the walls of the enclosure.

Referring now to the drawing which shows in the single figure thereof a transverse, cross-sectional View, taken essentially at right angle to the axis of the annulus, of one embodiment of a device in accordance with the present invention, it being understood that such illustration is non-limitative in character, reference numeral 1 designates therein a tore, for example made of aluminum and constituting the envelope or enclosure. A longitudinal magnetic field provided with constrictions in the lines of force 3 thereof at spaced points along the extent of the tore 1 is provided therein which is obtained by any suitable conventional means known in the prior art. For example, these means are constituted in part by six magnetic coils 2 regularly spaced along the extent of the annulus which are supplied from a suitable source or suitable sources (not shown) in such a manner as to produce lines of force directed in the same direction along the circular axis of the toric enclosure. The lines of force 3 present thereby constrictions at 4 within the region or locations of the windings 2 and diverge intermediate these regions or locations of windings 2 in such a manner as to constitute effectively six magnetic bottles forming a closed chaplet. Reference numeral 5 designates in the single figure the pumping means while reference numeral 6 designates the means for admitting the plasma which is confined within the magnetic bottles by the lines of force 3. Since the pumping means 5 and the particle injecting means 6 may be of any suitable type, known in the prior art, they are shown only schematically herein.

According to the present invention, high-frequency energy is injected into the coaxial space formed by the wall of the enclosure or vessel 1 and the plasma confined within the magnetic bottles which high-frequency energy propagates in closed circuit in the direction of arrows 7. The high-frequency energy is thereby injected into the space in accordance with well known techniques used with ultrahigh-frequency circulators, for example, across a directional coupler including a wave guide 8 disposed tangentially to the tore 1 and terminated by means of a matched load 9. The wave guide 8 communicates with the enclosure 1 through coupling apertures 10 which are so spaced as to produce the desired directional coupling effect whereby the interior space of the wave guide 8 is connected or coupled with the evacuated enclosure 1. The wave guide 8 itself is excited with a predetermined high-frequency electromagnetic wave energy from an amplifier 11 itself fed from an oscillator 12 both of which are of conventional construction and are, therefore, shown only schematically. The frequency of the oscillator 12 is thereby adjusted to produce optimum effect of the realized confinement.

The operation of the confining device in accordance with the present invention may be readily explained from the fact that the high-frequency field exercises on the plasma a transverse force or pressure which opposes the transverse diffusion of the particles and therefore the escape thereof across the walls of the magnetic bottles.

While we have shown and described one embodiment in accordance with the present invention, it is understood that the same is not limited thereto, but is susceptible of many changes and modifications within the spirit and scope of the present invention and we, therefore, do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

We claim:

1. A plasma confinement device comprising an evacuated essentially toroidally-shaped envelope, means for effectively filling said envelope with plasma, means for producing in said envelope a steady magnetic plasmaconfining field extending essentially over the entire tore, and means for injecting into said envelope ultra-highfrequency waves in such a manner as to propagate substantially in closed circuit and substantially in a single direction within the space comprised between the plasma and the walls of said toroidal envelope to thereby exert by the high frequency field produced by said waves transverse forces on the plasma and therewith prevent the escape of plasma particles across the Walls of the plasmaconfining field.

2. A plasma confinement device comprising an evacuated essentially toroidally-shaped envelope, means for ef fectively filling said envelope with plasma, means for producing in said envelope a steady magnetic plasma-confining field extending essentially over the entire tore and having constricted lines of force at substantially equidistant cross-sections of said tore, and means for injecting into said envelope ultra-high-frequency waves in such a manner as to propagate substantially in closed circuit and substantially in a single direction within the space comprised between the plasma and the walls of said toroidal envelope to thereby exert by the high frequency field produced by said waves transverse forces on the plasma and therewith prevent the escape of plasma particles across the walls of the plasma-confining field.

3. A plasma confinement device according to claim 1, wherein said last-mentioned means includes a wave guide and a directional coupler for said ultra-high frequency waves operatively connecting said wave guide to said envelope, and means for supplying said ultra-high-frequency waves to said wave guide through said directional coupler.

4. A particle confining device comprising an evacuated enclosure of substantially toroidal shape, means effectively constituting within said enclosure at least one magnetic bottle, means eifectively filling said enclosure with said particles, and means for reducing the escape of said particles through the walls of said magnetic bottle including means for supplying high-frequency electromagnetic energy into said enclosure in such a manner as to propagate substantially in closed circuit and substantially in a single direction within the space comprised between the plasma and the walls of said toroidal enclosure to thereby exert by the high frequency field produced thereby transverse forces on the plasma and therewith prevent the escape of lasma particles across the walls effectively formed by said magnetic bottle.

5. A plasma particle confining device comprising an evacuated enclosure having a substantially endless shape, means for establishing within said enclosure a plasmaconfining magnetic field effectively forming a magnetic bottle, means for efiectively filling said enclosure with said plasma, and means for reducing the escape of the plasma particles through the walls of said magnetic bottle including means for supplying high-frequency electromagnetic energy to said enclosure in such a manner as to propagate substantially in closed circuit and substantially in a. single direction within the space comprised between the plasma and the walls of said enclosure to thereby exert by the high frequency field produced thereby transverse forces on the plasma and therewith prevent the escape of the plasma particles across the walls effectively formed by said magnetic bottle.

6. A particle confining device according to claim 5, wherein said last-mentioned means includes a directional coupler.

7. A plasma confining device comprising an evacuated enclosure of approximately annular shape, means effectively constituting within said enclosure at least one magnetic bottle, means for effectively filling said enclosure with said plasma, and means for reducing energy losses in said plasma including means for supplying high-frequency electromagnetic energy to said enclosure in such a manner as to propagate substantially in closed circuit and substantially in a single direction within the space comprised between the plasma and the walls of said enclosure to thereby exert by the high frequency field produced thereby transverse forces on the plasma and therewith prevent the escape .of plasma particles across the walls effectively formed by said magnetic bottle.

8. A particle confining device according to claim 5, wherein a plurality of magnetic bottles are effectively formed in said enclosure.

Foster Mar. 11, 1958 Luce Mar. 1, 1960 

1. A PLASMA CONFINEMENT DEVICE COMPRISING AN EVACUATED ASSEMBLY TOROIDALLY-SHAPED ENVELOPE, MEANS FOR EFFECTIVELY FILLING SAID ENVELOPE WITH PLASMA, MEANS FOR PRODUCING IN SAID ENVELOPE A STEADY MAGNETIC PLASMACONFINING FILED EXTENDING ESSENTIALLY OVER THE ENTIRE TORE, AND MEANS FOR INJECTING INTO SAID ENVELOPE ULTRA-HIGHFREQUENCY WAVES IN SUCH A MANNER AS TO PROPAGATE SUBSTANTIALLY IN CLOSED CIRCUIT AND SUBSTANTIALLY IN A SINGLE DIRECTION WITHIN THE SPACE COMPRISED BETWEEN THE PLASMA AND THE WALLS OF SAID TOROIDAL ENVELOPE TO THEREBY EXERT BY THE HIGH FREQUENCY FIELD PRODUCED BY SAID WAVES TRANSVERSE FORCES ON THE PLASMA AND THEREWITH PREVENT THE 